#region Copyright

// The contents of this file are subject to the Mozilla Public License
//  Version 1.1 (the "License"); you may not use this file except in compliance
//  with the License. You may obtain a copy of the License at
//  
//  http://www.mozilla.org/MPL/
//  
//  Software distributed under the License is distributed on an "AS IS"
//  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
//  License for the specific language governing rights and limitations under 
//  the License.
//  
//  The Initial Developer of the Original Code is Robert Smyth.
//  Portions created by Robert Smyth are Copyright (C) 2008.
//  
//  All Rights Reserved.

#endregion

using NoeticTools.StateEngine.Rules;


namespace NoeticTools.StateEngine.States
{
    public class CurrentState<TContext, TState, TStateEvent> :
        ICurrentState<TContext, TState, TStateEvent>
        where TContext : class
    {
        private readonly IStateMap<TContext, TState, TStateEvent> stateMap;
        private TContext currentContext;

        public CurrentState(TState initialState, IStateMap<TContext, TState, TStateEvent> stateMap)
        {
            this.stateMap = stateMap;
            CurrentStateRules = stateMap.GetStateRules(initialState);
            CurrentStateRules.OnEntering();
        }

        public IStateRules<TContext, TStateEvent> CurrentStateRules { get; private set; }

        public TContext State
        {
            get { return currentContext; }
        }

        public TContext OnEvent(TStateEvent stateEvent)
        {
            CurrentStateRules.OnEvent(stateEvent);
            return currentContext;
        }

        public TContext OnEvent<T>(TStateEvent stateEvent, T arg)
        {
            CurrentStateRules.OnEvent(stateEvent, arg);
            return currentContext;
        }

        public void ChangeTo(TState toState)
        {
            CurrentStateRules = stateMap.GetStateRules(toState);
            currentContext = null;

            CurrentStateRules.OnEntering();

            if (currentContext != null && (currentContext as IState) != null)
            {
                ((IState) currentContext).OnEntering();
            }
        }

        public void ChangeTo<T>(TState toState, T arg)
        {
            CurrentStateRules = stateMap.GetStateRules(toState);
            currentContext = null;

            CurrentStateRules.OnEntering(arg);

            if (currentContext != null && (currentContext as IParameterizedState) != null)
            {
                ((IParameterizedState) currentContext).OnEntering(arg);
            }
        }

        public void SetContext(TContext context)
        {
            currentContext = context;
        }
    }
}